Hello
We recently upgraded the version of OpenSSL used in our application from
0.9.6c to 0.9.8e. Everything is fine except I have found that some of our
code was using memcpy() to 'save' and 'restore' EVP_CIPHER_CTX structures.
I understand now from looking at the OpenSSL code that this use was invalid
since we should not assume that an EVP_CIPHER_CTX can be correctly copied
via a simple memcpy().
My question: Is there a valid way to copy an EVP_CIPHER_CTX structure? I
have created a function which does this as a hack to get us up and running:
int EVP_CIPHER_CTX_copy(EVP_CIPHER_CTX *out, const EVP_CIPHER_CTX *in)
{
int retval = EVP_CipherInit_ex(out, EVP_CIPHER_CTX_cipher(in),
in->engine,
NULL, /* key */
NULL, /* iv */
in->encrypt);
if (retval == 1)
{
memcpy(out->cipher_data, in->cipher_data, in->cipher->ctx_size);
}
return retval;
}
Our goal is really to save and restore the cipher state of an RC4 cipher
context. It does not seem to be possible to ask an EVP_CIPHER_CTX to save
and restore it's internal state. Any ideas would be welcomed?
Sam Elstob
Product Developer
Triometric
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